To investigate the effect of pH on the rate of enzyme action.
The effect of pH on the rate of enzyme activity - sample questions
- Explain the term substrate in relation to enzyme activity
Substrate is the substance or sometimes food product that an enzyme works on. All enzymes are specific which means they act on a particular substrate based on the active site.
- To what group of biomolecules do enzymes belong?
- Name the enzyme that you used in this experiment and where you obtained the enzyme
Catalase released from celery
- Name the substrate upon which it works
Hydrogen peroxide
- Name two enzymes other than the one you investigated in this experiment & state their site of production & site of effect & substrate
Amylase released by the salivary glands into the mouth where it acts on starch to break it down to maltose.
Pepsin released in the stomach where it acts on proteins to break them down to peptides.
- Name the factor you altered during this experiment
The pH
- State how you altered this factor
We used different pH buffers- 4, 9 & 12
- Name the factors that you kept constant during this experiment
We kept temperature at 25 degrees as this is the optimum temperature & we kept the volume of substrate & enzyme constant also
- How did you keep these factors constant?
We kept the temperature constant by using the same water bath & measured an agreed volume for the enzyme & substrate each time
- State how you measured the rate of reactivity
We measured the amount of foam produced per unit time
- What are the products released in this experiment?
Oxygen & water
- What was the purpose of the washing up liquid in this experiment?
To trap the oxygen & water & create foam, this would allow us to see the amount of foam produced
- What were the results of this experiment?
That pH 9 is the preferred pH of plant enzymes
- Would the result be the same for an animal enzyme? Explain your answer
No, animal enzymes tend to prefer pH 7
- State the control you used in this experiment
We boiled and cooled catalase to denature the enzyme
- What is meant by a denatured enzyme?
An enzyme that has lost its 3D shape & therefore the active site is altered & the enzyme is permanently denatured.
